The present invention relates to a pneumatic radial tire suitable for use on heavy-duty motor vehicles such as trucks, buses or the like.
Recently, pneumatic radial tires have been used on heavy-duty vehicles such as trucks, buses or the like as well, and their superior properties such as high-speed performance, abrasion resistance and low fuel consumption have been exhibited. In this type of pneumatic radial tire for heavy-duty vehicles, a reinforcement layer in the tread portion is comprised of metal cords and has remarkably high rigidity so as to withstand the heavy load.
However, when this type of heavy-duty pneumatic radial tire having a tread portion with high rigidity is used, a high internal pressure is applied inside, and once the tire is caught in ruts in a road, the tire is subject to an excessive external force by the road when it is forced out of the ruts. This poses a problem in that a wandering phenomenon in which the steering wheel becomes uncontrollable is produced.
In order to solve this problem, the availability of a heavy-duty pneumatic radial tire with which a rut-related wandering phenomenon hardly occurs while maintaining the superior properties inherent in pneumatic radial tires such as high speed performance, abrasion resistance, and low fuel consumption has long been anticipated.